-LRB- CNN -RRB- -- What is the value and impact of international aid ? In an era of global austerity , this is a question that is frequently posed by policymakers and the citizens they represent .

The truth is , it is actually quite hard to measure . But there are important questions about both the quantity and quality of aid that must be answered .

Contrary to popular perception , aid is not one homogenous entity or a single transfer of money from donor to recipient countries . The term `` international aid '' actually covers a wide variety of things , including food and commodities , advice and training , and debt relief .

In 2011 -- the last year we have comprehensive data for -- total development aid from rich countries stood at nearly $ 150 billion , according to the Investments to End Poverty report . Only $ 59 billion identifiably involves the transfer of actual cash to , for example , recipient governments , NGOs operating on the ground or special project funds .

Aid in kind makes up another $ 25 billion . Most of this is food aid , which is used to tackle acute hunger -- but even this form of aid is not without controversy . Many donors avoid shipping actual food to developing countries , aware that it destroys local markets and harms local farmers .

Research demonstrates that food aid can be poor value for money , especially when food grown in donor countries is shipped to the developing world . Sorghum shipped from the United States is 200 % more expensive than it is in Chad and almost 100 % more than in Sudan , according to Development Initiatives calculations . Despite this , the United States and Japan continue to make extensive use of food shipments .

Perhaps even more surprising is the fact that large amounts of aid money never actually leave rich countries .

As much as $ 22 billion -- or 20 % of bilateral aid spending -- is spent on activities in donor countries or put towards the cancellation of debt . This includes funds to cover housing , food and other services for the first 12 months of refugees ' stay in the donor country . It also includes public spending on universities to cover the costs for students from developing countries . In 2011 , $ 4.5 billion was spent on refugee costs , $ 3.5 billion on university costs and around $ 7.5 billion on debt relief .

As important as these expenditures may be , they do not result in any transfer of resources to developing nations . These schemes may of course be beneficial to recipient countries in the long term -- for example , contributing to capacity development if students return to their countries . But it is undeniable that these schemes are at odds with the common perception of aid as financial support transferred from donor to recipient countries to fight poverty .

These different elements of aid obviously have very different effects on economic development and growth . A dollar of cash will have a very different impact to a dollar 's worth of food or a dollar 's worth of a consultant 's time . It is difficult to understand just how bundling all of these items into one lump sum can allow us to draw meaningful and reliable conclusions about the value of aid .

This lack of clarity was part of the motivation for Investments to End Poverty -- a major new report that analyzes aid in all of its complexity . At Development Initiatives we reviewed each individual record of foreign aid from OECD donors over the period 2006-2011 -- over a million rows of data . Now , for the first time ever , we can see just how much aid flows between specific countries and , crucially , what that aid consists of .

The results are striking . For example , according to our calculations , Italy and Denmark both gave very similar levels of bilateral aid , just above $ 2 billion , in 2011 . But almost 70 % of Italy 's aid stayed in the country , spent on refugee costs and debt relief , whereas around 70 % of Denmark 's aid resulted in a transfer of resources to developing countries .

On the recipient side , some countries that appear to receive considerable funds in fact receive a lot less than advertised . Our research found that of the $ 7.5 billion in aid reported as given to the Democratic Republic of Congo in 2011 , more than $ 5 billion was not transferred to that country , and consisted instead of debt relief .

All of this matters because we are at a crossroads in international development . In the last few decades , we have seen unprecedented progress in alleviating poverty , as recognised by world leaders meeting at the United Nations General Assembly in New York in September . There is a growing consensus that we can end extreme poverty by 2030 .

The truth is that we can not meet this goal without international aid . While FDI and remittances undoubtedly contribute to economic growth in developing countries , aid is the only international resource flow which can be targeted explicitly to improve the lives of the poorest people around the world .

In sub-Saharan Africa alone , 400 million people live in extreme poverty and require interventions that are targeted and complementary to existing support to lift them out of it . Without the support of international aid , most poor people will be left behind .

If we want to maximize the impact and reach of international aid , we need to ensure that every dollar is spent as efficiently as possible . We can only do this with better information and a clear understanding . Then policymakers in both donor and recipient countries can make better and more informed decisions , and civil society can better monitor progress and hold them to account .

The opinions expressed in this commentary are solely those of Charles Lwanga Ntale .

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Impact of international aid is hard to measure , says Charles Lwanga Ntale

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large amounts of aid money never actually leave rich countries , he adds

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But extreme poverty can not be ended without international aid